Finn and Jake, meet Fionna and Cake
by GreatDarkNoodleKing
Summary: This is an idea I had. Marceline casts a spell and the separate worlds of Finn and Fionna collide and become one. Everyone is exactly the same, yet the only people getting along are the Bubblegums... Will things ever become normal?
1. Opening

**Okay, so Adventure Time isn't really one of my favorite shows… To be honest, I can't stand half of the characters, and I hate how they're drawn. The noodle arms bother me… There are only a select few characters in the show that I actually like. Two that I adore. But I watched an episode the other day and now an idea has popped into my head and I really want to write it. So, without flames or hate mail, please enjoy…**

**Finn and Jake, meet Fionna and Cake.**

"Okay, okay, so maybe that _was_ a bad idea," Finn said with a happy chuckle as he and Jake his dog walked back to their tree house. Jake laughed and nodded, waving one finger up and down, wiggling it absently as he did.

A sudden female voice called out, "Finn! Jake! Guys!" Both turned around in confusion, only to find it was just Marceline with her umbrella over her head.

"Oh, hey Marceline, what's up?" Finn asked with a toothy smile.

Marceline floated over and lifted her hand under her shade and she asked, "Okay, I don't wanna scare you guys or anything, but I think you might not wanna go to your tree-house tonight…"

"Why?" Jake asked, "Is it infested with worms again?"

Marceline giggled and said, "No, nothing like that…" But her face fell and she said softly, "But I accidentally cast a spell last night… And when I woke up there was another me in my house… Only… he was a guy…"

"WHAAAAAT!" Finn and Jake shouted in unison, waving their noodle arms around wildly.

"Yeah, and so I think it did the same to you guys…" she explained further.

Jake asked, trying to clarify, "So there might be girl versions of us in our tree-house?" Marceline nodded, and the boys looked at each other.

Immediately they both jumped into action and ran as fast as they could to their tree-house. Marceline flew after them, shouting about how it was a bad idea and that they needed to stop, but they didn't listen.

Finn kicked the door open, and was immediately met with a girl in blue, wielding one of his swords.

"Hey! That's mine!" he yelled, jumping at her and trying to grab it.

But a cat suddenly jumped toward him, hissing loudly. Then Jake jumped into the fray and he stretched toward the cat, when suddenly…

"STOP!"

Finn and Jake recognized one voice as Marceline. The other sounded a lot like her, but it sounded…male...

Everyone turned and looked, to find Marceline floating next to a guy vampire with short messy black hair. Finn and Jake stared at him in shock. Their female doubles stared at Marceline.

"Who're you?" Finn demanded, pointing and yelling.

The male Marceline proudly put a hand on his hip and cocked his head to the side, saying smugly, "I'm Marshall Lee, the Vampire King."

The female Finn shouted at Marceline, "And then, who're you?"

"I'm Marceline, the Vampire Queen," Marceline responded, just as smugly.

Marshall hissed at her, "You can't be the queen if I'm king!"

"Well you can't be king if I'm queen!" Marceline spat back.

Finn, Jake, and their female doubles all looked at the vampire duo and then at each other. Jake growled at the cat, and the cat hissed at him in response.

"Anyway, Fionna, I told you and Cake not to go to the tree-house! Why didn't you listen to me?" Marshall Lee asked, completely turning his back on the angry Marceline.

Marceline turned to the boys and she hissed, "Yeah guys, why did you ignore me when I told you it'd only be trouble?"

Marshall growled lowly, "I asked first." Marceline hissed at him and looked back at Finn, waiting angrily for her answer.

Fionna answered first. "I just didn't think it was true…" She blushed a little and said, "Sorry Mar…" Marshall sighed, but he said he'd give her a break because they were friends.

"Your name's Fionna?" Finn asked, looking at the girl in surprise. He finally noticed she had a bunny hat on.

"And yours is Finn," Fionna said, lowering her weapon and straightening out a little, "So our names are opposite each other…"

"Why Cake?" Jake asked, "Cake isn't my name is girl form…"

Cake hissed, "You got a problem with cake? **Dog**?"

The two snarled and hissed and growled at each other until Fionna told Cake to chill and Finn told Jake to relax. Then the two looked at each other and their eyes shimmered.

Finn and Fionna felt their cheeks burn with heat, lost in a turmoil of emotions. Finally, Fionna spoke.

"Your hat is hideous…" she asked the question, and Finn's eyes popped into white wideness and they stared at each other in surprise. "Do you even have a neck?"

**LOLOLOL. I shall write more. I like the idea. Guess who my favorite characters are… Guess…**


	2. The Prognosis

**You know what? I hate the name they gave to Marshall Lee… I liked my name better… The name I made up for him was 'Marmasire'. Why? So that when he introduces himself, he can say, "I'm Marmasire, the King Vampire." And have it rhyme like Marceline does when she introduces herself… I hate Marshall Lee as his name… I like my fake name better. So in my head, that's his name. Oh, and you guys were almost right with your guesses.**

**My number one favorite is a tie between Marceline and LSP. (By the way, am I the only one who noticed Fanfic messed up on that?) And my second favorite is Cake. **

**Well, without further weirdness from me, here's the second Chapter of…**

**Finn and Jake, meet Fionna and Cake…**

Finn had never been so…weirded out before in his life! He meets his female double, and the first thing she says is that she hates his hat? The fact that there was a girl version of himself that didn't just exist in Ice King's imagination was weird enough, but to see that she hates him was even more bizarre.

Looking away from her for a moment, Finn looked at Marshall Lee and he asked, "So, are you like, her friend?" He pointed at his female double.

"Yeah… So? Marceline is your friend, right?" he asked, floating closer to Finn. Finn nodded and Marshall said, "Then likewise, I'm Fionna's friend."

Jake and Cake still didn't seem to like each other much, but at least they had stopped hissing and growling at each other. Still… Nobody really wanted to fight each other any more than they had to, so Fionna kept Cake by her side, and Finn kept Jake by his.

"So Marceline, how do we fix this?" Finn asked.

Marceline smiled nervously and said, "Well, I tried all the spells I knew, but nothing really worked… So… I was kinda hoping you guys might have a magical artifact that could help…" Marshall Lee snickered when she said she didn't know how to fix it, so Marceline hissed viciously at him.

Finn looked at Jake, Jake looked at Finn, and Jake whispered, "I don' think we have anythin' like that, bro…"

Finn spoke to Marceline, "Um… I don't really think anything we have could fix this…" Fionna spat to herself, "Not surprising." And Finn frowned to himself.

Marshall Lee floated in thought for a moment before asking, "Isn't Gumball really good with Sciency stuff, Fio?" Finn blinked a few times, but he quickly realized he was talking to his girl form.

Fionna thought for a moment before asking, "You think science might be able to fix this, Mar?"

"Sure! Worth a shot, right?" And so everyone hurried to where this 'Gumball' lived. Finn had no idea, but obviously Fionna did. But as he began to see the Candy Kingdom coming over the horizon, Finn quickly understood.

They all rushed into Princess Bubblegum's palace, with Fionna and Marshall Lee up in front. But Finn quickly hopped in front of them, shouting for his beloved candy princess.

She showed herself, and she smiled softly at them. "Finn, hey!" Finn was incredibly happy to see her, but he skidded to a stop when he saw a taller, male, short haired, pink haired man appear beside her. His heart sank into his gut.

Fionna looked just as horrified as Finn upon seeing Bubblegum, but Marshall Lee looked intrigued. Marceline was confused by the man with hair like Bubblegum's, and she whispered to herself, "What is he wearing?"

"Bubblegum, who's this guy?" Finn asked, trying to cover his jealousy.

Fionna looked at Finn and asked, "Bubblegum?"

Bubblegum smiled and said, "Oh, yes. You see, the strangest thing happened to me this morning. I woke up and found that there was another me in my home. His knowledge of all things science rival mine. And he's so noble; I figured I didn't need to call anyone about this." Finn's jaw dropped halfway through her explanation, so Bubblegum added that last part to try and soothe him.

Fionna looked at her like she was a demon witch, before she asked, "Gumball, why didn't you call me?"

"Well, Fionna, I didn't really think she was evil… So I saw no real logical reason to call for a hero," Gumball replied with a smile.

Marshall Lee floated over to Bubblegum and he asked her, "And how old are you, sweet-cheeks?"

Finn scowled at him for that, but Fionna jumped up and grabbed his pointy ear and pulled him back down near her.

"Sorry about Mar, he likes pretty girls…" Fionna said, not really wanting to apologize, but she was mad her friend was hitting on the girl who seemed to be getting along a little too well with Gumball.

"Oh, it's alright," Bubblegum said, "I'm kind of used to it…" She glanced at Finn, then she asked, "So why are you all here in such a hurry, anyway?"

"Oh, well, we all thought you could use your science to fix this problem of us having another us…" Finn explained, leaving out the fact that Marshall had originally suggested the male Bubblegum for help.

Marshall Lee tried to argue that fact, but Marceline shushed him by smacking him on the forehead. Marshall Lee scowled at her for it, but he shut up.

"Why would I do that?" Bubblegum asked. "Gumball is such a wonderful man; I thought it would be wonderful to have him around all the time."

"And I thought that since Princess Bubblegum is so agreeable, she'd have no trouble in sharing this lovely palace with me…" Gumball added.

Finn and Fionna looked like they had literally died. Jake caught Finn as his knees gave way, and Cake caught Fionna as she fainted.

Marshall and Marceline looked at each other, each with an equally worried expression…

**Well, there will be more later. I like my stupid little idea.**

**Can you figure out who they're going to go to for help? Anyone? Anyone?**


	3. Useless

**Listening to Underclass Hero… Inspired…! Watched the Fionna and Cake episode just a minute ago. A little disturbed. But at the same time, even more inspired! Lord Monochromicorn kinda freaked me out for a minute or two… And Ice Queen's eyebrows were a detail I hadn't noticed until now… Lumpy Space Prince had a moustache! HA! It's impossible to picture in my mind.**

**Finn and Jake, meet Fionna and Cake- The Third Chapter-**

"Look, is it my fault? Why are you so mad?" Marshall Lee was asking as he floated with Marceline under her umbrella and Finn, Fionna, Jake, and Cake all walked. He was addressing Fionna at the moment, who was pouting angrily at him.

"Why'd you hit on her?" Fionna snapped back.

Marshall immediately whined/yelled, "She was pink! It was so close to red…! I just got hungry! It's not my fault!"

"She's bubblegum, dude," Finn said, just staring ahead steadfastly. Marshall blinked and looked at Marceline.

"Bonnie's made out of bubblegum, that's why she's called Princess Bubblegum," she explained.

"So Gumball's made of bubblegum too?" Fionna asked Cake. Cake shrugged and suddenly her tail began twitching and fluffing up.

"Oh yeah, so where're we going anyway?" Marceline asked.

Fionna, Marshall, and Cake each looked at Finn, who simply replied, "The one person who can tell us everything we need to know…"

**Meanwhile…**

"So what do you do for fun?" Ice King asked, sitting down at an ice table and allowing Gunther to hop onto his lap.

A much more attractive female version of himself sat opposite him, Ice Queen, and she responded, "I kidnap Princes."

"Wow, I kidnap Princesses! That's such a coincidence!" Ice King said with a slightly nervous chuckle. Ice Queen looked at him funny, but she smiled at him and his little penguin friend after Gunther started flapping his wings excitedly.

"Ice King!" The sudden yell startled both evil ice people, but Ice King hopped up and used his beard to fly over to see who it was. He was promptly knocked down by a kick from a boy in blue.

"Finn!" he whined, "You're making me look bad in front of my guest!"

Finn grabbed Ice King's shirt and he yelled, "Tell us how to fix this!" Ice King went 'huh' and his jaw dropped when he saw Fionna and Cake walk into the room.

"Ooh oooooohhhh…! Fionna! Cake! Marshall!" he threw Finn off of him and Ice King ran up and began touching and looking over the three characters he made. Fionna slapped his hand away multiple times, Cake slashed at him, and Marshall made false attempts to bite him.

"Oh, oh, you guys are real! Oh this is too good to be true! And here I thought I was just hallucinating that Ice Queen was real!" Ice King was having a fangasm over the reality of his characters, while Fionna had to keep Ice Queen away from Finn. (Maybe she mistook him as a prince?)

Finally Finn couldn't take anymore. He slapped Ice King and shouted, "Ice King! Fix this! They're not supposed to be here! Tell us how to send them back!"

Jake added in a 'yeah' and used his magic to buff himself up a bit, just to let Ice King know they were serious.

Rubbing his cheek, Ice King whimpered, "I don' know how to fix this… I jus' made 'em up… I didn't do anything wrong… Besides, I like the Ice Queen. She's just like me…" And he waved his arms happily and smiled at his metaphorical and word specified bride.

Finn shouted angrily and let out a wonderfully loud yawp before hopping out Ice King's window and running outside. "Finn!" Jake called after him, hopping out and chasing him until they were both too tired to run.

Cake lowered Fionna down on her back, while Marshall and Marceline each floated down and all of them stared at Finn and Jake.

"Well… I guess we could all try and get along, right?" Fionna offered nervously. She glanced at Marshall and Marceline, both of whom glared at each other when she suggested that.

After a while everyone decided they'd just go home and try and figure everything out. Well, sort of… Finn refused to get off the ground. He kept shouting about how Bubblegum was gonna fall in love with "that big stupid smart gummy guy". Fionna swallowed in fear when he said that and tried to argue it wouldn't happen, but she wasn't sure herself.

Jake finally calmed him down and told Finn that maybe the spell would wear off in a few days and then everything would be totally normal afterwards. At this point, pretty much everyone hoped so.

**Wooh! Ice King is useless as usual! Now everyone's gonna be stuck like this! EPIC!**


	4. Don't Know

**My apologies for being away from this for so very very long… Kinda lost all time and inspiration for anything lately… So busy… Anywhooo… 40 reviews on this, wow! And though a lot is hate mail, I'm rather pleased to read it. People get so touchy if you insult something they like (I know because I do it too, don't have a cow…) Anyway, one question I got was if there will be a Flame Prince. I thought of this before Flame Princess was ever introduced to the story, so I'm not sure as of yet… If people want a Flame Prince, then let me know, otherwise… Meh…**

**Finn and Jake, meet Fionna and Cake**

"Man, this is butt…" Finn grumbled as he stomped in a circle with Jake. Jake was just trying to be sure he calmed down a little, but nothing he did was really helping. The two had wandered back to Marceline's along with Fionna, Cake, and Marshall- plus the vampire queen herself. Finn was outside fuming, trying to think of any ways possible to fix this.

Fionna was sitting on the porch with Cake, and Cake was muttering under her breath about Jake the dog. Still not getting along… Marshall and Marceline were both searching for spells on how to fix this. (So far no such luck) Marceline called up her dad through the portal spell she had taught Finn, and to her surprise, there wasn't a female double of him. Maybe he was so evil he was immune to changing genders in alternate worlds. Marshall had waved excitedly at the man he saw as his father, but Lord Aberdeen only recognized Marceline. Needless to say our vampire king was thoroughly angry and confused.

"Ice King's no help; He actually LIKES that freaky Ice Queen!" Finn shouted out of nowhere, startling Fionna, who hadn't really been paying attention anymore. She was just looking at her swords or Finn's swords… but… copies…? The double everything was confusing the lump out of her…

Jake sighed after a while and said, "Well, Finn, he made her up so that she'd be just like him, ya know? Of course he's gonna like her…"

Frowning, the heroic blue clad boy plopped onto the ground and grumbled angrily.

"Whaddya mean 'made her up'?" Fionna asked from the porch.

Jake turned to her, scowled quickly at Cake, and replied, "Well a while ago Ice King forced us to read this 'fan fiction' he wrote about us. And it had all of you guys in the story. But, you know, you didn't really exist…" Fionna frowned and thought in silence as Jake kept talking, "he wrote about how you were trying to save that Gumball guy from the Ice Queen and she tricked you by turning into him and going on a date with you…"

"Blech!" Fionna stuck out her tongue and shook her head side to side.

"He even included a guy version of my girlfriend…!" Jake finished. And the instant he finished that sentence, his eyes widened and his mouth fell below his furry jowls. "OH. MY. GLOB."

"What is it bro?" Finn asked, lifting his head from the ground.

"What if my girlfriend falls in love with her man twin!?" Jake then stretched into a massively huge dog and began sprinting away, screaming Lady at the top of his lungs. Finn grabbed his leg and hitched a ride before Jake got too far off. Fionna and Cake called the vampire pair and quickly gave chase to the two others.

When Jake got to Lady's, he found his girlfriend in a heated argument with a rainicorn that was solid black and not exactly a rainicorn. She looked extremely angry and that in itself gave Jake some relief to his fear of possible romance between the two.

"Lady!" he shouted, hopping to her side and shrinking down. Jake stared in shocked wonder at the black horse man before him just before the others arrived. Jake nuzzled his girlfriend's head gently, asking her how the pregnancy was going and then asked if everything was okay with this freak.

She answered him in her own language, which Finn still didn't understand, and Fionna gasped at seeing her. "Woah," she breathed. Marshall frowned.

"She's too colorful," he mumbled.

"I think she's beautiful," Fionna whispered, ignoring his insult. Monochromicorn stomped angrily at the new intruders.

"Hey!" Jake shouted angrily at him, "Be nice to Lady! She's gonna be a mom soon! She can't handle all this stress!" He jumped forward to attack the black horse, but Jake jumped in between and told him he was upsetting Lady. (Which was true, but Jake didn't want to admit it)

"Okay, so you've seen that there's another Lady Rainicorn guys, now what?" Marceline asked, frowning, "I could've asked my dad if he knew any spells-"

"You mean MY dad," Marshall grumbled, interrupting Marceline's thoughts.

Hissing, she spat, "You know what?"

Finn jumped in between them as well, shouting, "Guys, guys, stop! Not in front of Lady!" Jake quickly agreed before going back to cuddling and comforting his very upset girlfriend.

"We're gonna have to figure out some way to deal with this until we all find a way to fix it," Fionna said, stepping forward, "Maybe if it'd be okay, Marshall and Marceline could live together in that cave house…"

"Psh! I'm not spending one more minute with this girl," Marshall scoffed, floating over to Fionna's side, "I'm goin wherever you go, Fio…"

This didn't help her at all; because she still didn't know where she was gonna stay. Frowning, Finn said, "You can stay in the tree house with us if you keep your cat away from Jake… Or Jake, do you wanna stay here and take care of Lady…?" Jake only nodded, affirming his desire to stay with his girlfriend.

"Alright," Finn exhaled in frustration, but he walked back to the tree house with his friends. He didn't like the idea of staying with three people he didn't know and didn't really like, but if Marceline didn't have distractions, maybe she could find all sorts of magic to help them.

**Hours later at the tree house…**

"So you hang out with a bunch of hot princesses all the time?" Marshall asked, looking all the more curious as he saw photos of Bubblegum and Flame Princess in the tree house. He had been going through everything they had, sucking the red out of all the food they had, and was now exploring Finn's life.

"Yes," Finn replied before pulling the pictures away from his pale hands, "Now stop touching things."

"Who's the pretty lady with the spiky hair?" he asked, pointing to Flame Princess's photo.

"Nobody!" Finn spat, turning away from him and blushing. Marshall frowned and then floated over to Fionna and he patted her on the head, as if it were a drum.

She didn't really do anything, she just laughed a little bit and asked BMO to play more of the Ice King's secret tapes to her. For some reason Finn had kept them. She thought it was cute how Gunther did everything he did. When he sang Marceline's song in her wig she was a little creeped out, but Marshall found it hilarious and asked BMO to play it again.

Cake had snuggled off to sleep on the couch- she was happy so long as nobody tried to move her. Much like a real normal cat and not a magic one.

"Hey," Fionna suddenly addressed Finn. He looked up at her and waited for her to actually talk. She seemed to hesitate a lot- Finn noticed that several girls he knew did that… 'Cept LSP… She always spoke her mind whenever the lump she felt like it. He waited for what felt like forever- Marshall had to pat her face into annoyance for her to finally tell him to stop and she began talking.

"You think we'll ever get out of this? Think everything will be normal?" she asked, looking away now, staring out the window at the stars.

Finn sighed and looked at BMO's last video of the Ice King, where he apologized for anything he ever did to hurt anyone. "I don't know…"

"I just don't know…"

**Well, that's it for now I guess… I found out the nextest new episode of Adventure Time is bringing back Fionna and Cake and the one right after that is titled "Jake the dad". Looks like we're all gonna see those half-breed pups soon…! Should be fun… And maybe in the next Fio-Cake ep we can see if there's a male Flame Princess in the story. Oh, and if Marshall's actually gonna talk… That too…**

**Is BMO a guy?**


	5. Into the Night-O-Sphere

**Just watched the most recent Fionna Cake episode. MARSHALL TALKED! *flails* FINALLY! A voice to put to the face! Now I no longer have to hear the voice in my head when I read him talking…! **

**I got the Fionna Cake comic book volume one, too! There IS a Flame Prince. But he's feral… Which is… weird… Whatevs, I guess….**

**Gonna be honest, though, not sure how I feel about Flame Prince at all… Seee… I ship FioLee… REALLY bad… And… I dunno, he just throws it all off…. *angry frowny face* Don't worry, though, I'm not shipping in this story. It'd ruin the plot. Other than Finn Flame Princess like in the show, of course… Or did they break up…? Confused…..**

**Finn and Jake, Meet Fionna and Cake –Chapter Five—**

Once it started to really get dark outside, Finn asked Marshall if he could fly them somewhere. When he asked why, Finn didn't answer, he just frowned at him.

The two blond human children and Cake were currently sitting on Marshall the giant vampire bat's back. A soft orange glow in the distance made Finn smile; when it turned into the little hut he had made for Flame Princess, his smile grew.

Marshall set them all down, shrinking into his normal size, and he whispered to Fionna, "Why are we standing outside a burning house?" She shooshed him and watched as a girl made of fire came out to hug Finn.

The vampire boy blinked and asked, "Isn't that hurting him?" Fionna shooshed him again.

"You okay?" Finn asked his princess with a soft blush and a happy smile.

Flame Princess looked at him in mild confusion for a moment, before she noticed the three others standing a little ways behind Finn. She gasped and asked, "Who're they?" She went closer to them, and she quickly noticed that Fionna had basically the same clothes on as Finn. Turning to him, she asked, "Is she a water elemental? How come she's got your pack?"

"Well, uh, turns out Marceline messed some stuff up. And now everything's all gobbledeegoop… Apparently we all have doubles- just, if you're a boy, they're a girl and if you're a girl, then…" His voice trailed off as Flame Princess whispered a soft 'oooooohhhh'.

"So, is your name Finn, too, then?" she asked Fionna, who blushed in embarrassment.

Cake hopped forward, hissing a little, saying sassily, "Her name's Fionna!" Flame Princess jumped a little in surprise, but she didn't run away or even back away. After all, Cake was still just a cat…

Fionna patted Cake's head gently, saying, "Easy, Cake," and then she asked Flame Princess, "Have you seen a boy made of fire? I think that's basically why we showed up here…" She looked at Finn and asked, "Right?" Finn nodded.

Flame Princess blinked for a moment, but she shook her head. "Nah, haven't seen anything… If I do, I'll let you know, kay?" Finn nodded and hugged her again, ignoring the fact that his shirt scorched in a few spots.

Once the goodbyes were finished, the four of them started heading back to the tree house. Marshall refused to carry them this time, so Cake did. (Fionna made sure to call him lazy for that.)

"Soooo….." Marshall said, resting his hands behind his head, "She was hot…" Finn scowled at him, drawing a sword from his pack. Fionna beat him to it, however, and punched Marshall's cheek.

Slipping the sword back inside, Finn asked if they could go to Marceline's and see if she had found anything. Marshall grumbled something under his breath at that, but Fionna punched his arm and told him to be quiet. If Finn tried to do that to Marceline she'd kill him- apparently this vampire didn't mind getting beaten up…? Finn was still pretty confused by the whole clone thing. Weren't they all the same…? He didn't get it…

They all hopped into Marcie's cave house, frowning when they found her not there. But the giant flaming portal told them where she was.

"Anybody up for a trip to the Night-O-Sphere?" Finn asked.

"Not if I'm just gonna be ignored by my dad again," Marshall grumbled, floating in a circle above their heads with his arms folded over his chest.

"He's Marceline's dad, too, and you guys got brought to our world," Finn said, frowning up at him, "So she's tops to you." Marshall muttered something under his breath and floated into the portal. Finn, Fionna, and Cake followed suite.

**Sorry it's so short… I'll try to update soon…. Ish… I hope…? I have no clue… The show updates too fast- I'm so behind!**


End file.
